The use of a series resonant circuit on the primary side allows a nearly sinusoid current to be formed in the transformer, which produces corresponding current flows (and high efficiencies) on the secondary side. The LLC converter name is based on an additional resonance circuit consisting of a coil (L), primary inductor for the transformer (L) and condenser (C).
L10 is the nominal life expectancy for all technical objects. It means that at least 90 percent of the product achieves the indicated service life. The life expectancy is provided in revolutions (for fans in millions) or in hours. L10 hence makes a qualitative statement about the life expectancy of a bearing or fan.